street clothes       
noun [ plural ] mainly US uk/ˈstriːt ˌkləʊðs/ us/ˈstriːt ˌkloʊðs/
 平常穿的衣服,便装
ordinary clothes that people wear in public
  He was wearing street clothes, not a uniform. 他穿的是便装,不是制服。 
 A defendant has a right to wear street clothes at trial. 被告有权在审判时穿着自己平常的衣服。 
 - More examples
 - The patient was wearing a gown over her street clothes.
 - I would think the uniforms are cheaper than street clothes.
 - The young Noel Coward once arrived at a literary event in full evening dress, only to find everyone else in street clothes.